1. Field of the Invention
The present invention relates generally to the provision of feedthrough penetrations in hermetically sealed vessels and, more particularly, is concerned with an apparatus and method for changing feedthrough connectors in a pressurized spacecraft hull.
2. Description of the Prior Art
For carrying out materials research and production in space as well as many other applications requiring a space environment, an Industrial Space Facility is being constructed for launch and initial operation in the early 1990's. ("Industrial Space Facility" is a trademark of Space Industries, Inc.) The facility is designed to be a reusable, remotely controlled, free-flying space vehicle in low earth orbit. The facility will provide a pressurized shirtsleeve environment with sustainable power, cooling, and telemetry capabilities.
Plans are for the facility to remain in orbit for an extended time, for instance, 30 years. If the facility is to have a useful lifetime of 30 years in orbit, then it must be maintainable. Thus, the environment of the facility must be controlled and the facility must be capable of regular servicing while in orbit. Specifically, atmosphere and temperature control are required in the interior of the facility to support certain manufacturing processes or experiments, and for man-tended periodic servicing.
Many spacecraft hull penetrations are necessary for supplying electrical signals and power to the interior and for furnishing fluids used for cooling and atmosphere. Feedthrough connectors can be installed in these hull penetrations, with cables connected to the outside ends of the connectors, using special winged nuts required for astronaut EVA service. However, winged nuts need not be used on the cable connectors which are inside of the hull. The use of nuts on the feedthrough connectors to fasten them to the pressure hull is avoided by making internally threaded holes in the hull matable with external threads on the feedthrough connectors. The feedthrough connector is thus installed in a threaded hole in the pressure hull similar to a bulkhead fitting, but without an external nut.
Since the facility is intended for a 30-year useful life, it is important that provision be made for maintainability. Some means must be devised which facilitates removal and replacement or repair of a feedthrough connector which becomes defective for any of several reasons such as the presence of a crack in an insulator which allows air leakage or of a faulty electrical connection. Consequently, a need exists for an approach to changing a feedthrough connector with minimum loss of air.